This proposal requests funds for the purchase of an Applied Biosystems 4000 QTRAP Mass Spectrometer and Data System. The instrument is linked directly to an Eksigent nano HPLC system affording LC/MS/MS capability and will be located in the Proteomics Center in the Stony Brook School of Medicine. Demand has now exceeded the ability to perform MS/MS experiments in the Center. This system will address this critical problem and will significantly promote the research objectives and laboratory productivity of eight distinguished scientists from Stony Brook University (SBU) who comprise the major users group. Additional biomedical research investigators will also have access as instrument. This mass spectrometer system will make directly available to these investigators important new techniques for the analysis of biomolecules, which are presently unavailable at SBU and inaccessible or difficult to obtain from other organizations. LC/MS/MS is unsurpassed for the characterization of molecules with a vital biomedical significance, including lipids, biopolymers such as peptides, oligonucleotides, and oligosaccharides and smaller compounds which are non- volatile, labile, or thermally unstable. Techniques for coupling a liquid chromatograph to a mass spectrometer through electrospray or atmospheric pressure chemical ionization sources now permit the routine analysis of these substances with ease and rapidity. New information dependent data acquisition routines permit full characterization of multiple compounds during a single injection. Quantitative methods employing sensitive LC/MS/MS techniques are essential for several investigators. The instrument will be operated and maintained by trained personnel at the Proteomics Center, and the Director will schedule daily operation and provide technical expertise for the users. An advisory committee will ensure access to the major users and other PHS- supported investigators and will be responsible for the long term operation of the instrument. Relevance Innovative biomedical research requires frequent access to the newest analytical techniques to advance knowledge of human diseases and to provide new treatments for these illnesses. The Applied Biosystems 4000 QTRAP instrument will permit low-level analysis of many biomolecules critical to the research efforts of NIH-supported investigators at Stony Brook. They will use the new, analytical techniques offered by this instrument to explore mechanisms leading to diabetes, cancer, and heart disease and help define new biochemical markers and medications for each disease state. [unreadable] [unreadable] [unreadable]